Flap gate



E. c. HILLMAN June l, 1937.

' FLAP GATE Filed May 29, 1936 3 Sheets-Sheet 1 l Fig. 2.

/J-Xf l I I June l, 1937. E. c. HILLMAN FLAP GATE Filed Mayl 29, 1936 3 Sheets-Sheet 2 Figli;

/A/vf/VTOR E. C. H/LL MA N,

ATTORNEYS June l, 1937.

E. C. HILLMAN FLAP GATE Filed May 29, 1956 5 Sheets-Sheet 3 m. E a m 7 A afm-mw. A I

Fig. 7.

Patented June 1, 1937 UNITED sra'rss FLAP GATE Eric Chester Hillman, Mapperley Park, Nottingham, England Application May 29,

1936, rSerial No. 82,619

In Great Britain January 26, 1935 Claims.

This invention is for improvements in and relating to flap gates or valves, particularly for drainage culverts, outfalls, and the like. It is usual to equip a drainage culvert or pipe, the

5 mouth of which is at times submerged under a head greater than that causing the discharge (as may be occasioned by the rise and fall of the tides in the case of a culvert that discharges into tidal Waters) with a flap gate or valve that will open readily under the discharge head but which, when the mouth is submerged by a greater head of water, will close to prevent flow back along the culvert. Such a valve should be comparatively sensitive, so that it will readily respond, by opening or closing, to small differences in head at one side or the other, and so that by Y opening fully it will not impede the flow. Therefore it is known to provide a counterpoise, but in such an arrangement the added complication 20 and the additional space necessary is a disadvantage. Wooden flapgates have also been used, but such gates are eflicient only when new, for they become waterlogged and loose their buoyancy.

An important object of the present invention is to provide a flapgate which possesses the requisite buoyancy and ease of operation without the disadvantages attendant upon the use of wooden flapgates or the incorporation of a counterpoise; ao'and according to this invention there is provided, in or for a drainage culvert, outfall or the like With a mouth which is adapted to be submerged, a apgate or valve of the kind that is suspended from an axis or pivots and is adapted to be opened by the pressure of liquid in theculvert against the head outside and to close when the external head exceeds that in the culvert, which gate is made of metal but has a specific gravity only slightly in excess of that of the liquid in which it is destined to work. For example, the specic gravity of a gate used at the mouth oi a drainage culvert would be in the order of 1.2 or less, but would of course be greater than unity. The desired low specic gravity is best ensured by makin-g the gate hollow, and if this is done the said gate may be made of common metal such as iron or steel.

A trouble experienced with submerged apgates is that silt accumulates outside them and holds them shut, even after the discharge head reaches that value which would normally ensure opening.

This is overcome by a feature of the present invention, according to which the flap gate is substantially sectoral in cross section, tapering up- 575 wards towards its axis or pivots; more specically, the gate is increased in thickness towards the bottom and has its bottom side curved in section to conform substantially to an arc struck from the gate axis. Therefore, although the silt accumulates below the thickened gate, it

(Cl. Z7 7-42) does not build up over the outer face thereof, and the only additional resistance to opening that is imposed by the silt is the frictional drag between it and the curved bottom surface of the gate.

According to a further feature of this invention, provision is made for ensuring a flow of water, when the gate is closed, over or about the lower parts thereof in such manner as to wash the silt away and to prevent its accumulation.y

In order that the invention may` be better understood a practical application thereof will now be described in detail with reference to the accompanying drawings in which Figure l is a front elevation of the gate,

Figure 2 is a sectional plan (on the line 3-3in Fig. 1) of the gate,

Figure 3 is a vertical section of the gate showing its installation,

Figure 4 is an enlarged detail.

Figure 5 is a front elevation of a gate of another shape,

Figure 6 is a vertical section through a modified form of gate, showing its installation, and

Figure 7 is a section through one side edge of a gate. Y

Throughout this description like reference numerals indicate like parts.

The drainage culvert i0 discharges into a river or other tidal water by way of a discharge mouth in the bank, which mouth is in a plane inclined somewhat to the vertical (the angle may be some 20 to 30, but this is not essential `for as shown in Figure 6 the mouth may be vertical) and is located a short distance above the bottom. The said mouth is provided with a ap gate Il, desirably rectangular in elevation (but as shown in Fig. 5 a circular gate may be employed), which is suspended from horizontal pivots I2 against a frame I3 and, when shut, lies against the face on which the culvert mouth is formed, wide gunmetal bearing faces being desirably provided on the frame and flap. This gate has no counterpoise.

As is clearly shown in Fig. 3, the said gate is ysubstantially sectoral in cross section, tapering upwards toward its pivots I2, and is built of metal in the form of a hollow fluid-tight float or container. The dimensions of the interior air-space are so proportioned that the specific gravity of the whole gate is slightly greater than that of the water in which it works, and hence it will open or close in response to only a very slight dilTerence in head between its two sides. Desirablyballast blocks, as indicated at Il .may be provided. These blocks may be of cast iron and may be spot welded or otherwise secured in position.

Desirably, the gate is suspended by two or more short links I4, the upper ends of which are pivotally attached to supports secured in the bank, (e. g. in the masonry of framework i3 of the sluice structure) and the lower ends `of which are pivotally attached to the upperedge of the gate. The lower edge l of the gate'is curved in section to conform'to an arc struck from the axis on which the gate is pivoted tor-- the links but in general the curvature will be so.

small that no appreciable advantage is lost by making it flat,as shown in Fig. 6, the essential feature being that the edge or bottom side I5 is upwardly inclined. Hence such silt as may be deposited on the river bed or the like, inthe angle between said bed and theY bank, accumulates in the space beneath this wide curved bottom edge or surface and does not materially impede the freeV opening of the gate, the thickness of the gate at the bottom and the degree of upward taper being such as to provide ample space for silt accumulation.

Further precautions are also taken to prevent 'the excessive accumulation of silt. At a suitable level in the height of the gate one or more nonreturn passages 1,9 are provided for conducting Water through the gate from the inner face to the outer face thereof. Each passage is closed at itsr outer face by a flap valve 2U, preventing reverse flow, and as will be appreciated from Fig. 4 each flap 20 is arranged to serve as a deflector and to deflect the water, issuing from the passage I9, down the outer face of the gate.V This downward flow of water washes away the silt at the base of the gate. By way of example the valve-controlled ushing passage i9 is shown lin the Figures l and 3 of the drawings approximately three quarters of the way up the gate, but it may be found advantageous to locate said passage at a llower position, say less than halfway up the gate as is shown in Figures 5 and 6.

It is preferred to build up the gate from sheet metal by welding. Referring to Fig. 7, the gate Aconsists of front and rear plates lla, IIb, welded to peripheral members a as shown. When the gate is ofY circular elevation (see Fig. 5) the member la may be constituted by a single piece of sheet metal of the appropriated developed form.

It will be noticed from these two gures that the width of the contact surface between the gate and the member 30 is small. Hence the danger .that foreign matter may come to rest on the joint face and so prevent the gate from shutting completely is minimized. Moreover, if twigs of wood, or the like, become lodged across the face they .are cut in two when the gate closes.

with a mouth which is adapted to be submerged,

equipped with a flap gate as hereinbefore specifled. A not unimportant advantage of the gate provided by this invention is that, as its specific gravity is such that it will almost float, it may easily be handled in water. YIn particular, erection or assembly, removal and repair, which with existing gates necessitate cranes for handling them, are facilitated. Thus at low tide a workman may remove the gate from its hinges and tow it (by the hooks or eyes I8) to a convenient place for repair. Similarly the gate can be towed into position for erection.

The invention also provides means whereby the specific gravity and/or the centre of gravity of the gate can be accurately adjusted to meet existing requirements or conditions, and this is effected by so constructing the gate that ballast can be inserted as required. One method of accomplishing this is by casting or constructing `stalled that the centre of buoyancy and the centre of gravity coincide, or nearly so. If thesetwo centres do not exactly coincide, it is preferable that the centre of buoyancy should be below, rather than above, the centre of gravity.

Where water is employed as ballast, same can be withdrawn or syphoned out by way of a cock at the top of the gate, when said gate is to be removed. Thus, when the ballast is withdrawn the 4gate is rendered buoyant and can, when dismounted, be towed away. A feature of the invention therefore resides in a hollow metal flap gate for an outfall or the like, arranged to be ballasted by added ballast until its specific gravity is only slightly in excess of that of the liquid in which itis destined to work.

I claimt- 1. A flap gate for an outfall mouth that is periodically submerged, of the kind that is pivotally suspended and is adapted to be opened by the pressure of liquid on the culvert against the head outside and to close when the external head exceeds that of the culvert, which gate is made of metal but has a specic gravity only slightly in excess of that of the liquid in which it is destined to work.

2. A metal flap gate for the mouth of a cul'- vert or the like adapted to be submerged, of hollow construction and in section of substantially sectoral shape, and having means for pivoting it with its narrow part uppermost, the lower wide edge of which gate approximates to an arc struck from the pivot.

3. In a hollow metal flap gate for the mouth of a culvert or the like adapted to be submerged, the specific gravity of which gate is only slightly greater than that of the liquid in which it is destined to work, a non-return passage leading from the inner side of said gate to the outer and means for delecting fluid issuing from said pas sage down the outer face of the gate. 4. The subject-matter of claim 3, wherein the deector is a flap valve for closing the passage.

5. At an outfall mouth that is periodically submerged by the water Vinto which the outfall discharges, a hollow metal flap gate pivotally suspended to open outwards when the head in the outfall exceeds that outside and to close when the external head exceeds that in the outfall, means pivotally suspending the gate, and removable` ballast in the' gate, which gate when ballasted is nearly but not quite buoyant inf the submergi-ng water but is buoyant when the ballast is' removed. Y

ERIC CHESTER HILLMAN. 

